Sofa



FIG. 1 is a partial front perspective view of a sofa showing my new design;

FIG. 2 is a whole front perspective view of the sofa of FIG. 1;

FIG. 3 is a left side elevation view of FIG. 2 with the right side elevation view being a mirror image thereof; and,

FIG. 4 is a rear elevation view of FIG. 2.

The broken line disclosure is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a sofa, as shown and described. 